Lubricating the inside of the cylinder wall is of major concern in the design of internal combustion engines. Conventionally, oil from the crank case is splashed up into the open cylinder. When the piston moves down in the cylinder, rings located on the piston wipe excess oil back into the crankcase from the inside wall of the cylinder. On each rotation of the crank shaft, oil is splashed up into the cylinder and the cylinder wall is lubricated.
With this technique, it has been difficult to control the amount of oil supplied to specific portions of the cylinder wall. Portions of the cylinder wall exist which experience more wear due to the piston's being forced against the wall at these points. Accordingly, it would be advantageous if special provisions could be made to provide more lubrication to these portions of the wall. Unfortunately, providing localized lubrication of the cylinder wall has been difficult using conventional lubricating methods.
Several proposals have been made in the past to lubricate cylinder walls.
U.S. Pat. No. 1,632,119 issued to Davenport is an early example. Davenport shoWs a groove in a cylinder wall which is packed with a corded packing material. The inside of Davenport's corded packing material is made to be flush with the inside of the cylinder wall. Oil, which is supplied from the backside of the corded packing material, is absorbed by the packing material and then flows onto the inside surface of the cylinder. With Davenport's packing material, oil from a reservoir is supplied to the corded packing material only at a few localized points. In order for the oil to lubricate the rest of the periphery of the cylinder wall, the oil must diffuse around the periphery of the cylinder through the corded packing material. The absence of an oil carrying channel behind the packing material, in combination with the fact that Davenport's ring is located low in the cylinder below bottom dead center (BDC), could result in poor cylinder lubrication.
U.S. Pat. No. 1,643,674 issued to Miller shows an oil ring located on the inside wall of a cylinder. Miller uses an annular oil carrying channel, however, Miller's ring involves discrete holes which lead from the oil carrying channel to specific locations inside the cylinder. These discrete holes, in combination with Miller's teaching that the oil ring is to be located below bottom dead center (BDC), may result in poor cylinder lubrication.
U.S. Pat. No. 1,630,547 issued to Tartrais shows another approach. Tartrais provides a means for supplying lubrication to the cylinder wall at a location above the bottom dead center position of the piston. Tartrais' shows discrete oil holes which lead from an oil supply into the inside of a cylinder.